This application relates to the art of indicators and, more particularly, to indicators that provide a visual or electrical signal to confirm that an element is rotating, or to measure the speed of rotation. The invention is particularly applicable to a magnetically operated indicator for indicating that a vacuum cleaner brush roll is rotating and will be described with specific reference thereto. However, it will be appreciated that certain features of the invention have broader aspects and may be used for other purposes or in other environments.
In a known type of indicator for confirming the rotation of a vacuum cleaner brush roll, one or more magnets are attached to the brush roll for rotation therewith. During rotation of the brush roll, magnetic flux cooperates with a coil attached to the vacuum cleaner housing adjacent the magnets for producing a voltage that energizes a light. In most arrangements of this type, the magnets are mounted at one end of the brush roll which is devoid of brush bristles. The absence of brush bristles at one end portion of the brush roll provides ineffective edge cleaning and also reduces protection against entry of strings or threads into the bearing at the end of the brush roll. In other arrangements where the magnet is not at the end of the brush roll, there is no indication of how the magnets are attached to the brush roll.
In accordance with the present application, a brush roll has a cylindrical outer surface with a recess therein for receiving a permanent magnet. The recess in the outer surface of the brush roll facilitates attachment of the magnet thereto and minimizes the possibility that the magnet will move axially along the brush roll.
In a preferred arrangement, the recess in the outer surface of the brush roll is a circumferential groove and the magnet is carried by a magnet holder ring which is received in the groove.
In another arrangement, the recess in the outer surface of the brush roll is a cylindrical bore that receives a cylindrical magnet.
In a preferred arrangement, the magnet is located on the brush roll in alignment with one of the carpet plate ribs that extend from front-to-rear across the nozzle inlet opening. Brush bristles then are provided on both opposite sides of the magnet between the magnet and both opposite ends of the brush roll.
In one arrangement, the longitudinally-split magnet holder ring is molded of plastic material in an expanded open configuration with spaced-apart ends at the longitudinal split so that the inner and outer ring peripheries do not form continuous circles. The magnet holder ring is contractible to a closed configuration by moving the ends toward one another while semi-circular inner and outer ring peripheral portions move together and provide circular inner and outer ring peripheries. This facilitates movement of the expanded magnet holder ring over the brush roll and contraction of same into the circumferential groove.
In another arrangement, the magnet holder ring is molded of plastic material with circular inner and outer peripheries and a longitudinal split. The ring is expandable by moving the ends away from one another so that the inner and outer peripheries are non-circular. This facilitates movement of the magnet holder ring over the brush roll into alignment with the groove so that the expansion force can be released for allowing the ring to contract into the groove.
Fastening devices may be provided on the opposite end portions of the magnet holder ring for holding same together or for attaching same to the brush roll. In addition, the inner periphery of the magnet holder ring and the opposite end faces thereof may have ribs thereon that cooperate with the bottom and sides of the groove in the brush roll to prevent rotation of the magnet holder ring relative to the brush roll.
It is a principal object of the present invention to provide an improved arrangement for attaching magnets to vacuum cleaner brush rolls.
It is also an object of the invention to provide an improved location for a magnet on a vacuum cleaner brush roll with respect to a vacuum cleaner carpet plate.
It is a further object of the invention to provide an improved magnet holder ring for attaching a magnet to a vacuum cleaner brush roll.
It is an additional object of the invention to provide a location of a magnet on a vacuum cleaner brush roll that improves edge cleaning and positioning of brush bristles on both sides of the magnet along the brush roll.